The design of the MRD DHR rolling stock is quite unlike most etched kits as Hubert Carr has tried to make an etched kit that can be assembled using adhesives?and that has etched details inside and out.
Personally, I would solder plastic card of I could so the 'glue it together' bits of the instructions were completely ignored and a perfectly satisfactory job was done using various grades of solder, my 25 watt iron and RSU.
Couplings will take some thought, I agree but, until I've put my EDM B Class together running a train isn't an issue.
BTW - glueing the B class is definitely NOT recommended!!
MRD kits cover three DHR goods prototypes but I don't think they've moved on to carriages yet, so Worsley is the only source for these.
Adrian